What Is the Value of k When (1, -1) Lies on the Graph kx²-xy+y²=5?

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Homework Statement



if (1, -1) lies on the graph of the equation kx^2-xy+y^2 =5 what is the value of k?

Homework Equations





The Attempt at a Solution


plugging in 1 and -1 for the respective x y values yielded 3.How would you go abut solving this?
 
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You solved it.
 
so would k=3?
 
Yeah, because k is a constant, ie the same for any point on the given graph, and if you enter the coordinates of any such point into the function's equation, k must be such that the equation in indeed an equality.
 
thanks!
 
screamtrumpet said:

Homework Statement



if (1, -1) lies on the graph of the equation kx^2-xy+y^2 =5 what is the value of k?

Homework Equations





The Attempt at a Solution


plugging in 1 and -1 for the respective x y values yielded 3.How would you go abut solving this?
I don't know what you did to not end up with an equation, but when you substitute (1, -1) into the equation above, you get another equation: k + 1 + 1 = 5, or k = 3.

screamtrumpet said:
so would k=3?
 
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